Milling & Baking News - November 30, 2004 - 25

sary. References at the end of individual
chapters refer not only to books and research papers but even include Internet
sites where appropriate.
"Wheat Flour Milling" in the current
edition provides a broad review of the
flour milling process from a description of wheat, the raw material, the mill
laboratory and through the entire milling
process.
More than merely academic discussions, the book addresses issues that
have significant importance for the
profitability of a milling operation.
Along these lines, an interesting point
early in the book is the fact that a fairly
regular decrease in flour yield occurs
as wheat kernels decrease in size. The
ash content of flour milled to the same
extraction level from small kernels is
significantly greater than that of flour
from larger kernels. Within the same
wheat variety, large kernels possess
lower protein content than small kernels.
The same tendency is found in the
protein content of flour from wheat
varieties with different-sized kernels.
However, comparison of protein content between the whole wheat flour and
the finished flour shows a smaller protein loss with the large kernels. Thus,
a higher flour protein content may not
be guaranteed by paying a premium for
high-protein wheat, if it is made up of
small kernels.
Recognizing that price is a major
factor in wheat-buying decisions, the
authors say experience has shown
that procuring grain with quality suitable for producing the desired flour
characteristics and maximizing flour
extraction is, in the long run, more significant than low price for ensuring the
economical operation of the commercial mill. They also note that millability
of wheat might be expressed in future
grading as an indexed number that
would be a composite of all milling
parameters and would allow the miller
to define the raw material by quality
characteristics.
Also stressed is the importance for
individuals responsible for growing,
buying, storing, handling and processing wheat to know the handling
systems in the elevator. Storage facilities, handling system and atmospheric
conditions, such as the grams of moisture per cubic meter of air outside and
within the storage facility, may signifi-

26 / Milling & Baking News, November 30, 2004

cantly affect the quality and value of
the wheat.
Part of the art of milling rests in
wheat blending because, due to natural variation in wheat qualities, various wheat blends bring about widely
varying milling results. At the same
time, the authors note that blending
models have been created that provide
procedures for responding to price and
technology changes.
According to the authors, a premix
program is the preferred method of formulating final mill mixes. This is done
in the blending section of the elevator,
and bins with accurate feeders are dedicated to this purpose. ... Some mills,
rather than changing the wheat mix for

'No other feature of flour
milling will change faster in
the future than automation
and process control ... On-line
instruments will be developed
to more accurately evaluate
the physical, rheological, and
chemical characteristics of
wheat and flour constituents.'
- From
"Wheat Flour Milling"

each flour type, blend base flours from
holding bins to generate the different
flour products.
Moving on the conditioning, they note
tempering is probably the only stage at
which the miller may modify the wheat's
physical and chemical state. The objective is to have all kernels in the tempered
wheat reach the same physical condition
before milling.
The authors project that the cleaning house of the future will need to be
more intensive and flexible to remove
all impurities that originate from
wheat loads of various origins. Today,
in the milling process, some impurities are removed along with the bran,
but some are lost into the flour in the
reduction process.
The cleaning house of the future will be
expanded to ensure that all impurities are
removed before milling. This will require
greater control of the cleaning machines
and more exotic methods of separation,

using computer-enhanced grain profile
analysis and on-line monitoring of wheat
cleanliness in the process.

A look ahead at industry makeup
Future trends in grinding suggest new
mills will be designed to reduce labor
and lower capital and manufacturing
costs. The roller mill will continue to
be the basic grinder but will be supplemented by more auxiliary machines to
reduce the number of process steps. The
two-high eight-roll roller mill will continue to develop because it saves space,
spouting, and sifters, thus reducing
capital cost. Grinding will be controlled
by computers that regulate gap and the
intensity of the grind, with feedback control. Compact mills are a growing trend
for specialty flour markets.
Also looking ahead, the authors note
gyrating sifters have become larger with
more sections or boxes in the drive frame
to save space and reduce cost. The largest
sifter at the present time has 10 sections,
which is believed to be the economic
limit in size. However, they acknowledge it may be possible to separate and
remove flour in the pneumatic collectors
to save space and sifters. A similar system
worked in small mills, but has limitations
in large units.
The purifier chapter acknowledges
there will be fewer purifiers in new mills.
Some of the disadvantages are that they
require monitoring by the miller, have
high capital and operating costs, and have
low capacity per unit of floor space. The
authors note these are not desirable features for a computer-controlled, compact
mill requiring supervision by personnel
only during the day. However, purifiers
will be used to clean granular products
such as farinas and semolinas. The use of
debranning machines decreases the need
for purifiers.
A mill design chapter acknowledges
that in recent years with mills reducing
staff and engineering services, most major
construction projects are now "turn-key."
Stressing that new mill concepts different from existing are probable, the authors see computer- and P.L.C.-operated
mills that will require minimal human
intervention or actual machine observation. They point to the increased use of
slip-form construction with minimal windows and openings. Tunnels to collect the
air from the system and feed it back to
various sections of the plant.
As consumers' tastes change, meet-

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Milling & Baking News - November 30, 2004

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